Chromium plating product and method for producing the same

ABSTRACT

According to a chromium plating product including a substrate, a glossy nickel plating layer formed on the substrate, a nickel plating layer containing titanium formed on the glossy nickel plating layer, and a trivalent chromium plating layer formed on the nickel plating layer containing titanium and having a microporous structure, the chromium plating product includes the trivalent chromium plating layer as the exterior, and has high corrosion resistance. Further, the control of a plating solution and plating conditions for obtaining the same is easy.

BACKGROUND OF THE INVENTION Field of the Invention

The present invention relates to a chromium plating product havingimproved corrosion resistance and a method for producing the same.

Background Art

Chromium plating has a silvery-white or black appearance, and thereforeis used as a coating film for decoration. In the chromium plating,hexavalent chromium has been used, however, recently, the hexavalentchromium affects the environment, and therefore, the use thereof hasbegun to be restricted, and it has shifted to a technique usingtrivalent chromium.

However, trivalent chromium plating has lower corrosion resistance thanhexavalent chromium plating. Therefore, a technique for improving thecorrosion resistance of trivalent chromium plating has been reported.For example, Japanese Patent No. 6110049 reports a technique forenhancing the corrosion resistance in a calcium chloride environment byforming a glossy nickel plating layer, a noble potential nickel platinglayer, and a trivalent chromium plating layer having at least either oneof a microporous structure and a microcrack structure in this order on asubstrate, and intentionally providing a potential difference within aspecific range between the glossy nickel plating layer and the noblepotential nickel plating layer.

However, in the trivalent chromium plating, it is necessary tointentionally provide a potential difference within a specific range,and therefore, the control of a plating solution and plating conditionsis complicated, and the technique was not practical.

SUMMARY OF THE INVENTION

In view of the above, an object of the present invention is to provide achromium plating product including a trivalent chromium plating layer asthe exterior and having high corrosion resistance, and a technique thatfacilitates the control of a plating solution and plating conditions forobtaining the same.

The present inventors made intensive studies for achieving the aboveobject, and as a result, they found that by providing a nickel platinglayer containing titanium under a trivalent chromium plating layer, theresulting product has high corrosion resistance, and the control of aplating solution and plating conditions for obtaining the same is easy,and thus completed the present invention.

That is, the present invention is directed to a chromium plating productincluding a substrate, a glossy nickel plating layer formed on thesubstrate, a nickel plating layer containing titanium formed on theglossy nickel plating layer, and a trivalent chromium plating layerformed on the nickel plating layer containing titanium and having amicroporous structure.

Further, the present invention is directed to a method for producing achromium plating product including a step of forming a glossy nickelplating layer on a substrate, a step of forming a nickel plating layercontaining titanium on the glossy nickel plating layer, and a step offorming a trivalent chromium plating layer having a microporousstructure on the nickel plating layer containing titanium.

Still further, the present invention is directed to a nickel platingsolution containing a powder of a titanium compound and/or titaniumions.

The chromium plating product of the present invention has high corrosionresistance, and therefore can be used for decoration of automobilecomponents, flush metal fittings, etc.

Further, in the method for producing a chromium plating product of thepresent invention, only a nickel plating layer containing titanium isprovided under a chromium plating layer, and the control of a platingsolution and plating conditions for obtaining the same is easy, andtherefore, a new facility or the like is not particularly needed.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a view showing a cross section of a preferred chromium platingproduct of the present invention.

FIG. 2 is a view showing a cross section of another preferred chromiumplating product of the present invention.

FIG. 3 shows views of appearances after a CASS test in Example 1, andComparative Examples 1 and 2.

DETAILED DESCRIPTION OF THE INVENTION

The chromium plating product of the present invention (hereinafterreferred to as “product of the present invention”) includes a substrate,a glossy nickel plating layer formed on the substrate, a nickel platinglayer containing titanium formed on the glossy nickel plating layer, anda trivalent chromium plating layer formed on the nickel plating layercontaining titanium and having a microporous structure.

The substrate of the product of the present invention is notparticularly limited, and examples thereof include metals such as brass,iron, and stainless steel, and resins such as ABS, PC/ABS, and PP. Theform of the substrate is not particularly limited, but, for example, adoor handle, an emblem, or the like. The substrate may be subjected to,for example, a treatment such as etching or electroless plating.

On the substrate, a glossy nickel plating layer is formed. The thicknessof the glossy nickel plating layer is not particularly limited, but itmay be provided at a thickness of, for example, 1 to 25 μm, preferably 2to 15 μm.

A nickel plating solution for forming the glossy nickel plating layer isnot particularly limited, but contains, for example, a nickel compoundsuch as nickel sulfate, nickel sulfamate, or nickel chloride, a pHbuffer such as boric acid or citric acid, and an organic compound suchas saccharin, allylsulfonic acid, or butynediol.

Plating may be performed using the nickel plating solution for 3 to 30minutes under the following conditions: anode: nickel electrode, bathtemperature: 40 to 60° C., and current density: 2 to 5 A/dm².

When the substrate is a resin, a semi-glossy nickel plating layer isformed between the substrate and the glossy nickel plating layer asneeded. When the semi-glossy nickel plating layer is formed, it ispreferred to provide a potential difference between the semi-glossynickel plating layer and the glossy nickel plating layer, and thepotential difference is not particularly limited, but is, for example,60 mV or more, preferably 70 to 150 mV. By providing a potentialdifference in this manner, corrosion in the depth direction issuppressed by the sacrificial corrosion protection of the glossy nickelplating layer having a low potential. The potential difference can bemeasured by an electrolytic electrometer such as an electrolyticcorrosion resistance measuring device or an electrolytic platingthickness measuring device.

On the glossy nickel plating layer, a nickel plating layer containingtitanium is formed. The titanium content in the nickel plating layercontaining titanium is not particularly limited, but is, for example,0.01 to 1 mass %, preferably 0.02 to 0.5 mass %, more preferably 0.05 to0.4 mass %. The titanium content can be measured using, for example, ananalytical instrument such as EDS or a gravimetric method by filmdissolution. Further, the form of titanium is also not particularlylimited, and for example, titanium ions derived from a titanium saltsuch as titanium sulfate or titanium chloride, a powder of a titaniumcompound such as titanium oxide or titanium nitride, etc. areexemplified. When the powder of a titanium compound is used, the averageparticle diameter is 0.05 to 1.0 μm, preferably 0.1 to 0.7 μm. Amongthese forms of titanium, titanium oxide is preferred, titanium oxidehaving an average particle diameter of 0.05 to 1.0 μm is more preferred,and titanium oxide having an average particle diameter of 0.1 to 0.7 μmis particularly preferred. Here, the average particle diameter is avalue measured by electron microscopic observation of the powder.Further, the state of titanium is also not particularly limited, and maybe any of a rutile type, an anatase type, and a brookite type, but arutile type is preferred from the viewpoint of stability.

The thickness of the nickel plating layer containing titanium is notparticularly limited, but it may be provided at a thickness of, forexample, 0.5 to 5 μm, preferably 1 to 3 μm.

A nickel plating solution for forming the nickel plating layercontaining titanium is not particularly limited, but contains, forexample, a nickel compound such as nickel sulfate, nickel sulfamate, ornickel chloride, a pH buffer such as boric acid or citric acid, anorganic compound such as saccharin or allylsulfonic acid, a powder of atitanium compound such as titanium oxide or titanium nitride, and/ortitanium ions derived from a titanium salt such as titanium sulfate ortitanium chloride. As a preferred nickel plating solution, the followingnickel plating solutions are exemplified.

<Nickel Plating Solution 1>

-   -   nickel sulfate: 200 to 400 g/L, preferably 230 to 330 g/L    -   nickel chloride: 20 to 70 g/L, preferably 30 to 60 g/L    -   boric acid: 20 to 60 g/L, preferably 30 to 50 g/L    -   sodium saccharinate: 0.5 to 5 g/L, preferably 1 to 4 g/L    -   sodium allylsulfonate: 0.1 to 2 g/L, preferably 0.5 to 1.5 g/L    -   titanium oxide: 0.025 to 1.5 g/L, preferably 0.1 to 1 g/L    -   pH 3.5 to 5.5, preferably 4 to 5    -   bath temperature: 30 to 70° C., preferably 40 to 60° C.

<Nickel Plating Solution 2>

-   -   nickel sulfate: 200 to 400 g/L, preferably 230 to 330 g/L    -   nickel chloride: 20 to 70 g/L, preferably 30 to 60 g/L    -   boric acid: 20 to 60 g/L, preferably 30 to 50 g/L    -   sodium saccharinate: 0.5 to 5 g/L, preferably 1 to 4 g/L    -   sodium allylsulfonate: 0.1 to 2 g/L, preferably 0.5 to 1.5 g/L    -   titanium sulfate: 0.1 to 2 g/L, preferably 0.15 to 1 g/L    -   pH 4 to 6, preferably 4.5 to 5.5    -   bath temperature: 30 to 70° C., preferably 40 to 60° C.

Plating may be performed using the nickel plating solution for 1 to 5minutes under the following conditions: anode: nickel electrode, bathtemperature: 40 to 60° C., and current density: 2 to 5 A/dm².

In the nickel plating solution, a powder of a metal oxide such assilicon oxide may be incorporated. In this case, the content is, forexample, 0.1 to 3 g/L, preferably 0.2 to 2 g/L.

It is not necessary to intentionally provide a potential differencebetween the glossy nickel plating layer and the nickel plating layercontaining titanium, however, it is preferred to provide a potentialdifference for further improving the corrosion resistance. The potentialdifference is not particularly limited, but is, for example, 1 mV ormore, preferably 20 to 90 mV, more preferably 30 to 60 mV. By providinga potential difference in this manner, the sacrificial corrosionprotection effect of the glossy nickel plating layer is increased. Thepotential difference can be measured using an electrolytic electrometer.Further, in order to provide a potential difference, for example, theconcentration of a component constituting the nickel plating solutionfor forming the nickel plating layer containing titanium may be changed,or a known potential regulator such as chloral hydrate may beincorporated in the nickel plating solution for forming the nickelplating layer containing titanium.

On the nickel plating layer containing titanium, a trivalent chromiumplating layer having a microporous structure is formed. The number ofmicropores is not particularly limited, but is, for example, 5,000 to40,000/cm², preferably 8,000 to 25,000/cm². Here, the number ofmicropores is a value measured by a copper sulfate method. The thicknessof the trivalent chromium plating layer having a microporous structureis not particularly limited, but it may be provided at a thickness of,for example, 0.05 to 0.5 μm, preferably 0.1 to 0.4 μm. Further, thetrivalent chromium plating layer having a microporous structure ispreferably black or white, and is particularly preferably black from theviewpoint of a design property.

As a trivalent chromium plating solution for forming the trivalentchromium plating layer having a microporous structure is notparticularly limited, but for example, a silvery-white trivalentchromium plating solution containing a trivalent chromium compound suchas a basic chromium sulfate, chromium sulfate, chromium chloride,chromium sulfamate, or chromium acetate, an aliphatic monocarboxylicacid such as formic acid, ammonium formate, or potassium formate, analiphatic dicarboxylic acid such as succinic acid, maleic acid, malicacid, citric acid, or triammonium citrate, a complexing agent such astartaric acid, diammonium tartrate, or sodium tartrate, a conductivesalt such as a sulfate such as potassium sulfate, ammonium sulfate, orsodium sulfate, a chloride such as potassium chloride, ammoniumchloride, or sodium chloride, or a sulfamate such as potassiumsulfamate, ammonium sulfamate, or sodium sulfamate, a pH buffer such asboric acid, sodium borate, potassium borate, phosphoric acid, ordipotassium hydrogen phosphate, saccharin or a salt thereof such assaccharin or sodium saccharinate, and a sulfur compound such as asulfur-containing organic compound having an allyl group such as sodiumallylsulfonate, allylthiourea, ammonium 2-methylallylsulfonate, or allylisothiocyanate, a black trivalent chromium plating solution furthercontaining methionine, cysteine, sodium thiocyanate, or the like, etc.are exemplified. By using the silvery-white trivalent chromium platingsolution, a white trivalent chromium plating layer is obtained, and byusing the black trivalent chromium plating solution, a black trivalentchromium plating layer is obtained.

Plating may be performed using the trivalent chromium plating solutionunder the following conditions: bath temperature: 25 to 60° C., anode:carbon or iridium oxide, and cathode current density: 2 to 20 A/dm² for1 to 15 minutes.

The product of the present invention has sufficient corrosionresistance, and therefore, a chromate treatment that is generallyperformed for enhancing corrosion resistance may not be performed on thetrivalent chromium plating layer having a microporous structure,however, it is preferred to perform a chromate treatment for furtherimproving the corrosion resistance.

Preferred embodiments of the product of the present invention are shownin FIGS. 1 and 2. The substrate in FIG. 1 is a metal, and the substratein FIG. 2 is an ABS resin.

The product of the present invention obtained in this manner issubjected to evaluation according to JIS H 8502, and has corrosionresistance showing a rating number (R.N.) of 9 or more.

Therefore, the product of the present invention is favorable fordecoration of automobile components, flush metal fittings, etc.

EXAMPLES

Hereinafter, the present invention will be described in detail byshowing Examples, however, the present invention is by no means limitedto these Examples.

Example 1 and Comparative Examples 1 to 2

Preparation of Plating Solution:

After the components shown in the following Table 1 were mixed, the pHwas adjusted to 4.5 with nickel carbonate or sulfuric acid, whereby aplating solution (hereinafter referred to as “MP nickel platingsolution”) for forming a nickel plating layer containing titanium(hereinafter referred to as “MP nickel plating layer”) was prepared.

TABLE 1 (g/L) Comparative Comparative Example 1 Example 1 Example 2nickel sulfate 280 280 280 nickel chloride 45 45 45 boric acid 40 40 40sodium saccharinate 1.6 1.6 1.6 sodium allylsulfonate 1 1 1 titaniumoxide*¹ 0.5 — — aluminum oxide — 0.05 — silicon oxide — 0.3 — zirconiumoxide — — 0.2 *¹rutile type, average particle diameter: 0.2 to 0.3 μm,manufactured by Fuji Film Wako Pure Chemical Corporation

Example 2

Production of Chromium Plating Product:

A test piece (size: 1 dm²) of an ABS resin was subjected to etching,catalyst application, chemical nickel plating, and copper platingtreatments. Subsequently, in order to form a semi-glossy nickel platinglayer, plating was performed so that the film thickness was 3 μm usingthe following plating solution under the following conditions: anode:nickel electrode, bath temperature: 55° C., current density: 3 A/dm²,and plating time: 5 minutes.

<Semi-Glossy Nickel Plating Solution>

-   -   nickel sulfate: 230 to 330 g/L    -   nickel chloride: 30 to 60 g/L    -   boric acid: 30 to 50 g/L    -   butynediol: 0.015 to 0.035 g/L    -   hexynediol: 0.15 to 0.35 g/L    -   chloral hydrate: 0.03 to 0.6 g/L

Subsequently, in order to form a glossy nickel plating layer thereon,plating was performed so that the film thickness was 3 μm using thefollowing plating solution under the following conditions: anode: nickelelectrode, bath temperature: 50° C., current density: 3 A/dm², andplating time: minutes. Incidentally, a potential difference(electrolytic corrosion resistance measuring device) between thesemi-glossy nickel and the glossy nickel was 100 mV or more.

<Glossy Nickel Plating Solution>

-   -   nickel sulfate: 230 to 330 g/L    -   nickel chloride: 30 to 60 g/L    -   boric acid: 30 to 50 g/L    -   sodium saccharinate: 1 to 4 g/L    -   sodium allylsulfonate: 0.5 to 1.5 g/L

Subsequently, in order to form an MP nickel plating layer thereon,plating was performed so that the film thickness was 1.2 μm using the MPnickel plating solution described in Example 1 or Comparative Examples 1to 2 under the following conditions: anode: nickel electrode, bathtemperature: 50° C., current density: 3 A/dm², and plating time: 2minutes. Incidentally, a potential difference between the glossy nickeland the MP nickel was 9 mV.

Finally, in order to form a trivalent chromium plating layer thereon,plating was performed so that the film thickness was 0.25 μm using thefollowing plating solution under the following conditions: anode: carbonelectrode, bath temperature: 40° C., current density: 10 A/dm², andplating time: 3 minutes to obtain a chromium plating product having ablack appearance. Incidentally, the number of micropores (copper sulfatemethod) in the trivalent chromium plating layer was about 10,000 to20,000 in each case.

<Black Trivalent Chromium Plating Solution>

-   -   basic chromium sulfate: 120 g/L    -   ammonium formate: 30 g/L    -   potassium chloride: 120 g/L    -   ammonium chloride: 100 g/L    -   ammonium bromide: 6 g/L    -   boric acid: 60 g/L    -   methionine: 20 g/L    -   iron chloride: 1.35 g/L    -   cobalt chloride: 0.7 g/L

With respect to the thus obtained chromium plating products, thefollowing CASS test was performed. The results are shown in Table 2.

(CASS Test)

The test was performed according to JIS H 8502. A test piece after theCASS test for 48 hours was evaluated based on the total corrosion rate,which was shown as a rating number (R.N.).

(Measurement of Titanium Content)

The titanium content in the nickel plating layer containing titanium ofthe chromium plating product was analyzed by EDS. The results are alsoshown in Table 2.

TABLE 2 Potential Number of difference between micropores in glossynickel trivalent plating layer and Ti chromium MP nickel plating CASScontent plating layer layer test (wt %) Example 1 18000 9 9.3 0.11 to0.36 Comparative 16000 11 9 or 0 Example 1 less Comparative 20000 8 7 0Example 2

From the results of the CASS test, it was found that by incorporatingtitanium oxide in the MP nickel plating layer, corrosion resistance isimproved without intentionally providing a large potential differencebetween the glossy nickel and the MP nickel and further even withoutperforming a chromate treatment after trivalent chromium plating.

Examples 3 to 7

Preparation of Plating Solution:

After the components shown in the following Table 3 were mixed, the pHwas adjusted to 4.5 with nickel carbonate or sulfuric acid, whereby anMP nickel plating solution was prepared.

TABLE 3 (g/L) Exam- Exam- Exam- Exam- Exam- ple 3 ple 4 ple 5 ple 6 ple7 nickel sulfate 280 280 280 280 280 nickel chloride 45 45 45 45 45boric acid 40 40 40 40 40 sodium 1.6 1.6 1.6 1.6 1.6 saccharinate sodium1 1 1 1 1 allylsulfonate chloral hydrate — — — 0.048 — titanium oxide*²— — — — 0.05 titanium oxide*³ 0.2 0.5 1.0 0.2 — *²average particlediameter: 0.2 to 0.3 μm, manufactured by Fuji Film Wako Pure ChemicalCorporation *³average particle diameter: 0.5 to 0.6 μm, manufactured byThermo Fisher Scientific, Inc.

Example 8

Production of Chromium Plating Product:

A chromium plating product was produced in the same manner as in Example2 except that the MP nickel plating solution prepared in Examples 3 to 7was used. The number of micropores in the trivalent chromium platinglayer, the potential difference between the glossy nickel plating layerand the MP nickel plating layer, the results of the CASS test, and theresults of measurement of the titanium content in each chromium platingproduct are shown in Table 4.

TABLE 4 Potential Number of difference micropores between glossy intrivalent nickel plating chromium layer and MP Ti plating nickel platingCASS content layer layer test (wt %) Example 3 9600 7 mV 9.3 0.09 to0.35 Example 4 18000 7 mV 9.3 0.31 Example 5 22000 7 mV 9.3 0.24 Example6 12000 40 mV  9.5 Not measured Example 7 5000 9 mV 9.0 Not measured

From the above results, in Examples 3 to 5 and 7, corrosion resistancewas favorable as they were even without intentionally adjusting thepotential difference. In Example 6, by intentionally adjusting thepotential difference to 40 mV, the corrosion resistance was furtherimproved.

Example 9

Production of Chromium Plating Product:

A chromium plating product was produced in the same manner as in Example2 except that the following white trivalent chromium plating solutionwas used.

<White Trivalent Chromium Plating Solution>

-   -   basic chromium sulfate: 64 g/L    -   ammonium formate: 20 g/L    -   potassium chloride: 140 g/L    -   ammonium chloride: 100 g/L    -   sodium chloride: 60 g/L    -   ammonium bromide: 6 g/L    -   boric acid: 65 g/L    -   chloral hydrate: 0.5 g/L

From the above results, even in the case of white trivalent chromiumplating using a chloride, corrosion resistance can be favorable.

Example 10

Production of Chromium Plating Product:

A chromium plating product was produced in the same manner as in Example2 except that the following white trivalent chromium plating solutionwas used.

<White Trivalent Chromium Plating Solution>

-   -   basic chromium sulfate: 64 g/L    -   diammonium tartrate: 30 g/L    -   potassium sulfate: 145 g/L    -   ammonium sulfate: 20 g/L    -   boric acid: 80 g/L    -   sodium saccharinate: 2.5 g/L    -   sodium allylsulfonate: 0.5 g/L    -   chloral hydrate: 0.8 g/L

From the above results, even in the case of white trivalent chromiumplating using a sulfate, corrosion resistance can be favorable.

Example 11

Production of Chromium Plating Product:

A chromium plating product was produced in the same manner as in Example2 except that a brass plate (size: 1 dm²) was used as the test piece andsemi-glossy nickel plating was not performed.

From the above results, even in the case where semi-glossy nickelplating was not performed for the metal material, the corrosionresistance of the trivalent chromium plating product can be favorable.

INDUSTRIAL APPLICABILITY

The chromium plating product of the present invention has high corrosionresistance, and therefore can be used for, for example, automobilecomponents, flush metal fittings, etc.

1. A chromium plating product, comprising: a substrate; a glossy nickelplating layer formed on the substrate; a nickel plating layer formed onthe glossy nickel plating layer and comprising titanium; and a trivalentchromium plating layer formed on the nickel plating layer and having amicroporous structure.
 2. The chromium plating product according toclaim 1, wherein the titanium in the nickel plating layer is titaniumoxide having an average particle diameter of 0.05 to 1.0 μm.
 3. Thechromium plating product according to claim 1 or 2, wherein the nickelplating layer has a titanium content of 0.01 to 1.0 mass %.
 4. Thechromium plating product according to any one of claims 1 to 3, whereina number per unit area of micropores in the trivalent chromium platinglayer is 5,000 to 30,000/cm².
 5. The chromium plating product accordingto any one of claims 1 to 4, wherein a potential difference between theglossy nickel plating layer and the nickel plating layer is 1 mV ormore.
 6. The chromium plating product according to any one of claims 1to 5, further comprising: a semi-glossy nickel plating layer formedbetween the substrate and the glossy nickel plating layer, wherein thesubstrate comprises a resin.
 7. The chromium plating product accordingto any one of claims 1 to 6, wherein the trivalent chromium platinglayer is black.
 8. The chromium plating product according to any one ofclaims 1 to 6, wherein the trivalent chromium plating layer is white. 9.A method for producing a chromium plating product, comprising: forming aglossy nickel plating layer on a substrate; forming a nickel platinglayer comprising titanium on the glossy nickel plating layer; andforming a trivalent chromium plating layer having a microporousstructure on the nickel plating layer.
 10. The method according to claim9, wherein the titanium in the nickel plating layer is titanium oxidehaving an average particle diameter of 0.05 to 1.0 μm.
 11. The methodaccording to claim 9 or 10, wherein the nickel plating layer containingtitanium has a titanium content of 0.01 to 1.0 mass %.
 12. The methodaccording to any one of claims 9 to 11, wherein a number per unit areaof micropores in the trivalent chromium plating layer is 5,000 to30,000/cm².
 13. The method according to any one of claims 9 to 12,wherein a potential difference between the glossy nickel plating layerand the nickel plating layer is 1 mV or more.
 14. The method accordingto any one of claims 9 to 13, further comprising, prior to the formingof the glossy nickel plating layer on the substrate: forming asemi-glossy nickel plating layer on the substrate, wherein in theforming of the glossy nickel plating layer, the glossy nickel platinglayer is formed on the semi-glossy nickel plating layer formed on thesubstrate, and the substrate comprises a resin.
 15. The method accordingto any one of claims 9 to 14, wherein a black trivalent chromium platinglayer is formed as the trivalent chromium plating layer.
 16. The methodaccording to any one of claims 9 to 14, wherein a white trivalentchromium plating layer is formed as the trivalent chromium platinglayer. 17-21. (canceled)
 22. The chromium plating product according toclaim 1, wherein the trivalent chromium plating layer is formed on thenickel plating layer such that the trivalent chromium plating layercontacts the nickel plating layer.
 23. The chromium plating productaccording to claim 1, wherein the trivalent chromium plating layer isformed on the nickel plating layer such that only the nickel platinglayer contacts the trivalent chromium plating layer.
 24. The chromiumplating product according to claim 1, consisting of the substrate, theglossy nickel plating layer, the nickel plating layer, the trivalentchromium plating layer, and optionally a semi-glossy nickel platinglayer formed between the substrate and the glossy nickel plating layer.25. The chromium plating product according to claim 1, wherein thetitanium in the nickel plating layer is titanium oxide having an averageparticle diameter of 0.05 to 1.0 μm, and a number per unit area ofmicropores in the trivalent chromium plating layer is 5,000 to30,000/cm².
 26. The chromium plating product according to claim 1,wherein the trivalent chromium plating layer is formed as an outermostlayer of the chromium plating product.